Ten thousand copies of the documents – inviting comments on a revised off-site emergency plan – were sent to homes within and just outside a 4km radius of the nuclear site. But the envelopes were not individually addressed and were only marked “Important Documents” – similar to markings on a range of “junk” mail.

A proportion may have ended up unopened in bins, emergency planning chief Andy Osman has conceded following criticism of the way the consultation has been handled.

“Royal Mail gave us a range of possible markings but in retrospect it may have been better to clearly identify the documents as relating to the Sizewell emergency plan review,” he said.

The draft plan suggests the current 2.4km zone – the area for which detailed emergency plans exist – is expanded to 4km to include the whole of the town of Leiston and an overall population of 6,500. The current zone covers only a small part of the town and a resident and working population of just 800 people.

So far, the public consultation, which ends on April 8, has attracted more than 100 responses from people by post and 75 online. Local councils and other organisations are also giving their comments.

Mr Osman said he hopes more people will give their views. All would be taken into account in drafting a final version of the plan for approval by the Office for Nuclear Regulation (ONR), he said.

People are invited to attend a “drop-in” session at Leiston Sports and Social Club between 3-7pm on Wednesday. The proposed new emergency plans will be on display and it is hoped officials from both ONR and the Department for Energy and Climate Change will be present to answer questions.

Extra copies of the consultation documents can be ordered by telephoning 01473 265321.